Extended range, gun fired guided projectiles including rocket motors are subject to failure because of the nature of the rocket motor and the gun fire environment. The enormous stresses including pressures and forces of the gun fire environment accelerate a projectile up to 12,000 g's. These stresses and high temperatures in the environment cause one or more of compression, expansion and possibly fracture of the rocket motor propellant that results in failure of the projectile, sometimes catastrophically.
In one example, where the rocket propellant is subjected to inertial loading from gun firing, corresponding compression forces cause propellant fractures that increase the surface area for burning. The fractured propellant burns in an unpredictable manner and negatively affects the range and accuracy of the projectile. In another example, where the rocket propellant is fractured from inertial based compression forces, the propellant undergoes adiabatic compression and prematurely initiates within the bore of a gun thereby causing a catastrophic failure of the projectile and gun.
In still another example, the high temperature environment in the gun barrel causes the rocket propellant to expand and fill a limited space. Subsequent ignition of the rocket propellant in the limited space creates unexpected high pressures within the projectile that unpredictably increase the burn rate of the propellant. Unpredictable burning of the propellant negatively affects the flight of the projectile including its range and accuracy.